Search

The Main Köpetdag fault (MKDF) of Turkmenistan is one of the longest (≈500 km) and the most rapidly straining (9.1 ± 1.3 mm/yr) faults of the Arabia–Eurasia collision zone, and yet, in contrast to adjacent parts of Turkmenistan and Iran, it has little in the way of observed seismicity. Field observations indicate a fresh paleorupture along an ≈100 km long section of the MKDF with abundant streams offset across it. We use WorldView-2 optical satellite imagery to measure geomorphic offsets and compile them into a cumulative offset probability density (COPD) function. The COPD yields two peaks in offset density at 7.5 ± 1.5 and 12.5 ± 1.5 m, when considering the highest and the lowest quality measurements, whereas the medium-quality measurements present a single peak at 9 ± 3 m. We are unable to separate peaks into distinct events when exploring the contributions of offset measurements along strike that have significant variability. The paleorupture displaces archaeological remains, including extensive field boundaries of likely medieval age, and a paleoseismic trench brackets the age of the most recent displacement at 600–800 yr B.P. From our measurements of displacement, we estimate that the most recent paleoearthquake had a moment magnitude (Mw) 7.6 ± 0.4 and yet is missing from earthquake records in nearby Iran, indicating that the paucity of historical earthquakes in Turkmenistan may be misleading. The Baharly, Döwgala, and Gökdepe segments of the MKDF, which extend eastward toward Aşgabat, do not show fresh surface expression. Infrared-stimulated luminescence ages of 3.4 ± 0.5 and 2.5 ± 0.2 ka from a river-cutting exposure along the Baharly segment predate the most recent paleorupture. We conclude that individual segments of the MKDF are capable of rupturing in major (Mw>7.0) earthquakes, with ends of individual ruptures possibly controlled by segment boundaries. The occurrence of major earthquakes and rapid slip rate suggests that the MKDF constitutes a hazard to a populated region of Turkmenistan and northeast Iran.

A signal mixer made of a transistor facilitates rich computation that has been the building block of modern telecommunication. Here we report that a neural cell is also a signal mixer. We found throughex vivoandin vivomeasurements that individual neurons mix exogenous (controlled) and endogenous (spontaneous) subthreshold membrane potential oscillations, thereby producing new oscillations. Furthermore, we demonstrate that the neural mixing dynamic is evident in human brain activity and is associated with our cognitive functions. Neural network oscillations have been observed in nearly every cognitive domain and species. Signal mixing enables single neurons to actively sculpt their network oscillations and utilize them for computational operations, which have only been seen in modern telecommunication until now.One-Sentence SummaryWe report that a neuron is a signal mixer akin to an electronic transistor capable of modulating oscillatory human brain dynamics.

The waking brain’s ubiquitous alpha oscillations are thought to play an important role in managing the brain’s resources, inhibiting neural activity as a function of their phase and amplitude. In accordance with this physiological excitability, perceptual and cognitive processes fluctuate with alpha oscillations. Here we demonstrate that the alpha rhythm can be manipulated with sound in a phase-dependent manner, showing that repeated phase-locked sounds alter the frequency of these oscillations in a spatially localised manner. We draw on oscillator theory to explore the origin of this frequency change, using phase-locked auditory evoked potentials to show a putative phase-reset mechanism, which is dependent on the amplitude of the endogenous alpha oscillations. Finally, we demonstrate the functional relevance of this approach by showing that we can modulate the transition to sleep, using sound, in an alpha phase-dependent manner. Overall, we conclude that the phase of alpha oscillations can be exploited in real-time, and highlight alpha phase-locked auditory stimulation as a powerful method by which to both selectively augment and investigate the brain’s pertinent oscillations.

Both grazing and fine fuels management are dependent on the temporal and spatial distribution of herbaceous biomass production. Rangeland and wildland fire managers can both benefit from knowing when and where there is excessive herbaceous biomass buildup. In this study, we compared modeled herbaceous biomass outputs from the Phytomass Growth Simulator (Phygrow) to observe and predict herbaceous production on desert, juniper, and pine sites on the Coconino National Forest in Arizona. Models were validated with: (a) 2 years of quarterly data, and (b) fire season-only data. The Phygrow model showed strong agreement between observed and predicted values year-round on the desert (r2 = 0.73) and pine sites (r2 = 0.69), and a lower, but positive agreement in the juniper sites (r2 = 0.54). Fire season predictions were strong for all ecosystem types (desert r2 = 0.89; juniper r2 = 0.62; pine r2 = 0.94), suggesting that the Phygrow model is well suited to provide valuable decision support information with which to address both rangeland and fire management objectives.

Deep brain stimulation (DBS) via implanted electrodes is used worldwide to treat patients with severe neurological and psychiatric disorders however its invasiveness precludes widespread clinical use and deployment in research. Temporal interference (TI) is a strategy for non-invasive steerable DBS using multiple kHz-range electric fields with a difference frequency within the range of neural activity. Here we report the validation of the non-invasive DBS concept in humans. We used electric field modelling and measurements in a human cadaver to verify that the locus of the transcranial TI stimulation can be steerably focused in the hippocampus with minimal exposure to the overlying cortex. We then used functional magnetic resonance imaging (fMRI) and behaviour experiments to show that TI stimulation can focally modulate hippocampal activity and enhance the accuracy of episodic memories in healthy humans. Our results demonstrate targeted, non-invasive electrical stimulation of deep structures in the human brain.

Luminescence thermochronology and thermometry can quantify recent changes in rock exhumation rates and rock surface temperatures, but these methods require accurate determination of several kinetic parameters. For K-feldspar thermoluminescence (TL) glow curves, which comprise overlapping signals of different thermal stability, it is challenging to develop measurements that capture these parameter values. Here, we present multiple-aliquot additive-dose (MAAD) TL dose response and fading measurements from bedrock-extracted K-feldspars. These measurements are compared with Monte Carlo simulations to identify best-fit values for recombination center density ($\rho$) and activation energy ($\Delta E$). This is done for each dataset separately, and then by combining dose-response and fading misfits to yield more precise $\rho$ and $\Delta E$ values consistent with both experiments. Finally, these values are used to estimate the characteristic dose ($D_0$) of samples. This approach produces kinetic parameter values consistent with comparable studies and results in expected fractional saturation differences between samples.

Aberrant neural oscillations hallmark numerous brain disorders. Here, we first report a method to track the phase of neural oscillations in real-time via endpoint-corrected Hilbert transform (ecHT) that mitigates the characteristic Gibbs distortion. We then used ecHT to show that the aberrant neural oscillation that hallmarks essential tremor (ET) syndrome, the most common adult movement disorder, can be transiently suppressed via transcranial electrical stimulation of the cerebellum phase-locked to the tremor. The tremor suppression is sustained shortly after the end of the stimulation and can be phenomenologically predicted. Finally, we use feature-based statistical-learning and neurophysiological-modelling to show that the suppression of ET is mechanistically attributed to a disruption of the temporal coherence of the aberrant oscillations in the olivocerebellar loop, thus establishing its causal role. The suppression of aberrant neural oscillation via phase-locked driven disruption of temporal coherence may in the future represent a powerful neuromodulatory strategy to treat brain disorders., Aberrant synchronous oscillations have been associated with numerous brain disorders, including essential tremor. The authors show that synchronous cerebellar activity can casually affect essential tremor and that its underlying mechanism may be related to the temporal coherence of the tremulous movement.

Aberrant neural oscillations hallmark the pathophysiology of numerous neurological and psychiatric disorders. Here, we first report a method to accurately track the phase of neural oscillations in real-time by a Hilbert transform that avoids the characteristic Gibbs distortion at the end of the signal, aka endpoint-corrected Hilbert transform (ecHT). The ecHT method maintains the same computational complexity class of the original Hilbert transform allowing implementation in simple digital hardware. We then used the ecHT method to show that the aberrant neural oscillation that hallmarks treatment-resistant essential tremor (ET), the most common adult movement disorder, can be noninvasively supressed via transcranial electrical stimulation at a fixed phase lag over the cerebellar hemisphere ipsilateral to the tremor movement. This was tested in a quadruple-replication randomized way including stimulation at 6 fixed phases, sham and without phase-locking. In a total of 11 subjects, the suppression of ET activity was sustained after the end of the stimulation and was phenomenologically predicted, post-hoc, from the features of the tremor movement before the start of the stimulation. To test for reproducibility, 6 of the original participants werer stimulated exactly the same way three years after the original experiments: the observed, significant stimulation response remained, i.e. responders continued to respond and non-responders did not. Finally, we used a highly-comparative feature extraction (> 8000 features) with statistical learning and neurophysiological computational modelling to show that the suppression of ET activity can be mechanistically attributed to a disruption of the temporal coherence in the tremor movement that can be originated in a higher bursting entropy at the cortico-olivo-cerebello-thalamic circuitry. The suppression of aberrant neural oscillation via phase-locked driven disruption of temporal coherence may represent a powerful neuromodulatory strategy to treat neurological and psychiatric disorders.

Aberrant neural oscillations hallmark numerous brain disorders. Here, we first report a method to track the phase of neural oscillations in real-time via endpoint-corrected Hilbert transform (ecHT) that mitigates the characteristic Gibbs distortion. We then used ecHT to show that the aberrant neural oscillation that hallmarks essential tremor (ET) syndrome, the most common adult movement disorder, can be noninvasively suppressed via electrical stimulation of the cerebellum phase-locked to the tremor. The tremor suppression is sustained after the end of the stimulation and can be phenomenologically predicted. Finally, using feature-based statistical-learning and neurophysiological-modelling we show that the suppression of ET is mechanistically attributed to a disruption of the temporal coherence of the oscillation via perturbation of the tremor generating a cascade of synchronous activity in the olivocerebellar loop. The suppression of aberrant neural oscillation via phase-locked driven disruption of temporal coherence may represent a powerful neuromodulatory strategy to treat brain disorders.

Autism spectrum disorder (ASD) is primarily characterized by impairments in social communication and the appearance of repetitive behaviors with restricted interests. Increasingly, evidence also points to a general deficit of motor tone and coordination in children and adults with ASD; yet the neural basis of motor functional impairment in ASD remains poorly characterized. In this study, we used magnetoencephalography (MEG) to (1) assess potential group differences between typically developing (TD) and ASD participants in motor cortical oscillatory activity observed on a simple button-press task and (2) to do so over a sufficiently broad age-range so as to capture age-dependent changes associated with development. Event-related desynchronization was evaluated in Mu (8–13 Hz) and Beta (15–30 Hz) frequency bands (Mu-ERD, Beta-ERD). In addition, post-movement Beta rebound (PMBR), and movement-related gamma (60–90 Hz) synchrony (MRGS) were also assessed in a cohort of 123 participants (63 typically developing (TD) and 59 with ASD) ranging in age from 8 to 24.9 years.We observed significant age-dependent linear trends in Beta-ERD and MRGS power with age for both TD and ASD groups; which did not differ significantly between groups. However, for PMBR, in addition to a significant effect of age, we also observed a significant reduction in PMBR power in the ASD group (p 13.2 years (p

We are currently witnessing a major transformation of twentieth-century institutions. It is not that the sovereign state, the business corporation or the other major institutions of national and international life are going away, but they are experiencing substantial ‘unravelling’. Driving this process are two underlying dynamics: the dramatic expansion of information and communication technology and a pervasive expansion of human capacity caused by wider access to education. The unravelling of institutions which results from these dynamics has three key elements. The first is globalization—a fundamental change in time–distance relationships and in the impact of physical and political boundaries. The second is the increased ability of single individuals or informally organized, non-hierarchic groups to solve complex problems, resulting in a ‘flattening’ of effective organizations. The third transformation is the ‘unbundling’ of services, as the ability of organizations to control information and markets declines. These transformations promise to change the relative competitiveness of various institutions.

Nationality has been a key identity in international relations for much of the modern period, and the marriage of “nation” and “state” produced a powerful polity – the national state – that dominated global politics. This article investigates the forces that “pushed” and “pulled” nations and states together and explores the factors associated with violent identity politics. It argues that while recent decades have witnessed increasing instances of divorce between “nation” and “state” and a simultaneous proliferation of identity conflicts, the likelihood that identity conflicts will be expressed violently depends both on the character of the state (the timing of state institutionalisation relative to the construction of national consciousness, the democratic or non-democratic nature of the state, and the national or non-national basis for the legitimation of state authority) and on the principal “marker” used to construct national identity (blood, language, culture, religion, or citizenship).

This article analyzes the Bush administration's vision of NATO and its future development. Examining the statements of president Bush and other high-ranking US officials, the article explores the ways in which the administration's understanding of NATO is embedded in its vision of world politics as an epochal struggle between good and evil. While evil has assumed a variety of faces in the past, in today's world it is manifested as tyranny and terrorism. The restoration of humanity's birthright of freedom requires the faith and moral courage to eradicate, rather than accommodate or compromise with, this evil. For the Bush administration, this conception of an ongoing war between the righteous and the poor of spirit logically implies the need for widened membership in NATO, a new partnership with Russia, an expansion of the theater of struggle from Europe to the world, and a transformation of the alliance's military capabilities.

(2003). The imperial logic of Bush's liberal agenda. Survival: Vol. 45, No. 1, pp. 131-154.

Models available in literature for predicting drag reduction scale-up are inadequate as they have been successful only over a narrow range of diameters. A new scale-up model is presented which equates dampening of turbulent velocity fluctuations by drag reducing additives to a reduction in the Prandtl mixing length. Flow and pressure drop data from a laboratory scale pipe along with shear viscosity measurements are sufficient to predict drag reduction scale-up in bigger diameter pipes. Using this approach, scale-up was successfully predicted over a diameter range of 7 to 154 mm for a surfactant-water system and 26.6 to 1194 mm for a polymer-oil system. Les modeles presentes dans la litterature scientifique pour la prediction de la mise a l'echelle de la reduction de trainee sont inadequats, ceux-ci ne fonctionnant que dans une gamme etroite de parametres. On presente un nouveau modele de mise a l'echelle qui fait intervenir l'amortissement des fluctuations de vitesse en regime turbulent par des additifs de reduction de trainee avec une reduction de la longueur de melange de Prandtl. Des donnees d'ecoulement et de perte de charge d'une conduite a l'echelle de laboratoire avec des mesures de viscosite de cisaillement sont suffisantes pour predire la mise a l'echelle dans des conduites de plus gros diametres. Par cete methode, la mise a l'echelle a ete predite avec succes pour des diametres compris entre 7 et 154 mm pour un systeme surfactant-eau et entre 26,6 et 1194 mm pour un systeme polymere-huile.

(1996). Sea Change: Interest‐based vs. cultural‐cognitive account of strategic choice in the 1890s. Security Studies: Vol. 5, No. 4, pp. 73-124.

Allison's Model III (governmental or bureaucratic politics) suggests that state policies reflect the parochial concerns of intragovernmental “players in positions” and the relative power of these players. This article offers a critical test. It examines a policy area—U.S. decisions on the composition of naval forces—in which we would, a priori, expect bureaucratic politics to have a maximum effect and which participants, observers, and scholars have routinely described as critically influenced by bureaucratic politics. This article employs statistical methods to assess whether outcomes have indeed been affected by the parochial priorities and perceptions of individuals who, because of their relative power and the rules of the game, have dominated the relevant bureaucratic action-channels. Contrary to the expectations of the bureaucratic politics literature—indeed, contrary to the reports of firsthand observers and the actors involved—bureaucratic politics do not seem to have mattered: knowledge of bureaucratic interests and power does not permit us to predict outcomes. The article then proceeds to suggest an alternative model of state behavior thatdoesprovide significant explanatory power: the article demonstrates that shifts in force posture can be modeled as a function ofideasandimagesrather than ofinterests. This gives rise to speculation that in explaining American foreign and security policy the name of the game is not, as Allison suggests, politics, but the competition of ideas for intellectual hegemony.

(1994). New money and old ships: Budget reductions and the “Hollowing Out” of the US fleet. Defense Analysis: Vol. 10, No. 1, pp. 79-90.